This invention relates to tape transports and more particularly to digital magnetic tape transports having an automatic tape load feature which incorporates a leader block attached to the end of the tape being threaded.
Systems which transfer a web member, such as magnetic recording tape, between a file reel and a machine reel often have an automatic loading path. The operator merely inserts a file reel containing tape, and pushes an automatic load button. Carefully located tape guides, which frequently include air jets, guide the tape along the loading path until the tape attaches to and begins winding on the machine reel. Sensors located along the tape path, which frequently include the beginning of tape and end of tape sensors, generate a load error signal if the tape does not load properly. In most existing systems, the end of the tape being threaded is shaped to have rounded corners, and is passed through the threading channel of the tape using air jets. As the end of tape approaches the machine reel, air jets force it between the flanges of the machine reel, and the tape is attached to the machine reel hub by a vacuum system through holes contained in the hub.
In another type of existing system, for example that described in U.S. Pat. No. 4,334,656, to Crawford et al., entitled "Automatic Tape Threading Apparatus For Magnetic Tape Transports", the file reel consists of a cartridge with a leader block that is attached to the end of the tape to be threaded. When the cartridge is inserted in this type of system, a coupling device connects to the leader block and pulls the leader block and tape through the tape path and inserts the leader block into the hub area of the machine reel. In this type of automatic tape threading apparatus, it is important that the slot in the hub of the machine reel be aligned properly with the path taken by the coupler in inserting the leader block into the reel hub. The alignment of this slot with the thread path is even more important during the unload process as the last wrap of tape is being unwound off the machine reel, the machine reel must stop at the exact position aligning the slot to the thread path so that the leader block can be removed from the machine reel without damage to the leader block and without breaking the tape.
There is need in the art then for apparatus to align the machine reel with the tape thread path both during initial threading of the tape into the machine reel and for aligning the machine reel as the last wrap of tape comes off the machine reel just prior to the unload threading operation.